New member here chasing some sage advise. My 2007 3.5 V6 ML Triton is producing a P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control) error code. It appears to occur on longer runs at about 40 minute mark. On shorter drives it doesn't appear and will actually clear its self after a few cycles of shorter trips. Triton seems to run fine when Check Engine Light (CEL) is on.

I've ordered a new Engine Coolant Temp (ECT) sensor and hope this will be the solution. Anyone else experienced this and better still found a solution?

Last edited by Newtron on Tue Nov 20, 2018 2:45 pm, edited 1 time in total.

Put the new ECT sensor in yesterday with no sealant tape or paste and so far no leaks following a 10 minute test run and a 50 minute school run (I know right ) this morning. Best result though is no CEL so far. Fingers are remaining tightly crossed and the best test will have to wait till next week when I can try a few hour long freeway journeys.

How good are those V6's? This must be about the third time that anyone's had an error code on an ML V6. I had just two in 5 years - one when the ABS unit self destructed and one when the apprentice filled the spark plug recess with water. Engine still ran, with just an occasional hiccup.

How good are those V6's? This must be about the third time that anyone's had an error code on an ML V6. I had just two in 5 years - one when the ABS unit self destructed and one when the apprentice filled the spark plug recess with water. Engine still ran, with just an occasional hiccup.

Thanks for the replay. I haven't had this beast long but did a fair bit of reading prior to buying a second hand 4x4. I initially thought a diesel would be the go but after reading about the more rigorous maintenance required on modern diesels and the relative reliability on the V6's (other brands included) my preference swung the way of the V6.

Not sure I want to start replacing the thermostat as surely the actual engine coolant temp isn't actually too low at 45kms into a drive on a 32 degree day? From reading the limited number of similar stories I can find where thermostats were replaced the P0125 CEL has persisted.